In modern motor vehicles, a plurality of electromotors are used, which take over actuating or control functions primarily in the area of comfort. In this context, each electromotor is connected with a circuit arrangement, through which the electromotor is switched according to the actuating or control functions required by the vehicle driver or by superordinated control devices. For this purpose, several switches are arranged on the circuit arrangement, which effectuate the forward running, the reverse running as well as the blocking of the electromotor.
The blocking of the resting electromotor is achieved electronically in a simple manner, in that the two terminals of the electromotor are short-circuited. In this regard, in connection with an externally forced rotation of the armature shaft of the electromotor, according to Lenz's law, the generated electrical power acts against or contrary to its causation, whereby the rotation of the armature shaft is maximally damped. This damping is sufficient to prevent the rotation of the armature shaft of the electromotor, for example, if components of low mass that are connected with the armature shaft via gear wheels act on the armature shaft during the acceleration or the deceleration of a motor vehicle.
In this context, the circuit arrangement becomes correspondingly more complex and costly, if the blocking of the resting electromotor is only to be effectuated for one rotational direction of the armature shaft, while the respective other rotational direction of the armature shaft shall remain rotatable without damping.